This is nothing new as FB has had Custom Audiences available for a while now, and you could also do this with 3rd party audience lists via cookie onboarding services like LiveRamp, etc.

What I'm wondering here is if Google will provide any way to upload this info to them anonymously similar to how Liveramp does it.

I personally won't be running these, but I'm curious if others are really comfortable with the idea of uploading their customer lists to Google (or FB or anyone else for that matter) in plaintext vs. going through a neutral middle-man that lets you just provide hashed values to get a match.

EDIT:

Looks like my reading comprehension failed this morning and they do allow you to upload hashed lists per their support doc. Also, to clarify, I have little doubt that Google, FB, etc. can't figure out who the people are. The main concern is with the people managing the AdWords accounts pulling/sending around plaintext email lists of all these customer records. That is often extremely sensitive and valuable company data that should never be sent around like that. From my experience, the people managing these campaigns are often not technical or experienced enough to think of risks like that. So hopefully the only way they can access such info is via someone who does have the knowledge/experience to say "yeah, plaintext lists of our customer emails are NOT something I'm going to be sending you a CSV of."